It marked a marginal improvement over what Sainz manged in Qualifying 2, when he recorded a 1:19.705s lap, but came after an error midway around the lap forced an aggressive final sector.
“I knew that (a 1:19.6s lap) would have given me top five, so I was chipping away,” Sainz said.
“The last lap I nearly messed up, I had a big moment in Lesmo 1 and I nearly lost it.
“Since then on, I had to drive like this (aggressively) and I'm actually shaking a bit because since Variante Ascari I really had to go for it.”
“I felt like I was nailing Q1 and Q2, and Q3 run one I didn't quite nail it,” he added.
“I was waiting for Q3 run two, and the lap didn't start very well and I was already needing some very strong final few corners.
“I really went for it, I risked a lot, and it paid off and as you can see, after the dive I did into Ascari I was like ‘whoa' that was way too late.”
Sainz's first effort in Qualifying 3 was a comparatively sedate 1:19.906s, a lap that would have left him seventh on the grid.
His near three tenth improvement therefore resulted in a four place gain for Sunday's race, which he expects to be somewhat of a rear-guard encounter.
“I'm not as good as P3 I think, but we're going to try to hang on there,” he reasoned.
“I mean, we had the Renaults this weekend that I thought were going to be quicker than us, but this lap helps.”
The Italian Grand Prix gets underway from 23:10 AEST tonight.